Dyfnwal Hen or
Dumnagual Hen ("Dyfnwal the Old") was a ruler of the
Brittonic kingdom of
Alt Clut, later known as Strathclyde, probably sometime in the early 6th century. His biography is vague, but he was regarded as an important ancestor figure for several kingly lines in the
Hen Ogledd or "Old North" of Britain. As an ancestor figure, he compares to
Coel Hen, another obscure figure credited with founding a number of northern dynasties.